Hydraulic hoist system



March 2, 1948. v KANE 2,437,161

HYDRAULIC HOI ST SYSTEM Filed March 21, 1940 3 Sheets-Sheet 1 1772201 $07" G/wawfl. Hams March 2, 1943. G. A. KANE 2,437,161

HYDRAULIC HOI ST SYSTEM 3 Sheets-Sheet 3 March 2, 1948. G. A. KANE HYDRAULIC HOIYSAT SYSTEMY Filed March 21, 1940 Patented Mar. 2, 1 948 UNITED STATES PATENT OFFICE HYDRAULIC HOIST SYSTEM Garold A. Kane, Minnea The Northern Pump polis, Minn, assignor to Company, Minneapolis,

14 Claims.

This invention relates to a hoist and a control mechanism therefor and especially to a hoist which is hydraulically operated. While said hoist may have various applications, one particular application thereof is for an a-mmunition hoist. With such a hoist used for carrying ammunition, such as shells, on a warship, it is desirable that the same operate quite rapidly. It is also desirable that in a flight or one movement of said hoist the same be accelerated rapidly to full speed and that it be decelerated gradually and brought to zero acceleration and velocity at the end of the flight. This is necessary in order to prevent movement of the shells on said hoist due to inertia of the shells in raisin-g or lowering the same, which movement is commonly referred to as shucking. The ideal curve of deceleration of said hoist would probably be a straight line. It is difiicult to have the deceleration curve follow accurately a straight line, although in the present invention the deceleration curve is substantially a straight line.

It is an object of this invention to provide a control mechanism for a hoist by means of which said hoist may be operated in distinct movements or flights, the movement of said hoist being accelerated or decelerated according to a fixed predetermined law.

It is another object of the invention to provide a hydraulic hoist system comprising a hoist driven by a hydraulic power unit which is in turn driven by a variable stroke pump, together with means for varying the stroke of said pump to give "a predetermined acceleration and deceleration to said hoist so that there is a definite fixed relation between the control means for varying the stroke of said pump and the deceleration of said hoist.

It is also an object Of the invention to provide a hydraulic hoist system comprisin a hoist, a hydraulic power unit connected thereto for moving the same, a variable stroke pump, means for varying the stroke of said pump to positively control the rate of movement of said hoist, a control means for said last mentioned means, means moved by the change of stroke of said pump for operating said control means and a flight control mechanism driven in direct ratio to the movement of said hoist for operating said control means.

It is a further object of the invention to provide a control mechanism for a hoist comprising a motor-driven variable stroke pump operating a hydraulic motor connected to said hoist, which control mechanism may-be automatically operated to move, accelerate and decelerate said hoist as desired.

It is a further object of the invention to provide a control mechanism as above set forth comprising a flight control mechanism directly connected to the hoist driving mechanism and cooperating with the means for varying the stroke of said pump.

Another object of the invention is to provide a hydraulic control and driving mechanism for a hoist comprising :a driven variable stroke pump, said stroke being varied-by hydraulic means to accelerate or decelerate the movement of said hoist, said, variation of stroke also acting to operate a cam for positively determining the rate of acceleration and deceleration.

It is further an object to provide a hoist and a motor-driven hydraulic control and driving means therefor, said control means including manually operated means for setting the hoist to be raised or lowered or to be set in neutral position, together with certain operating control electrical circuits having switches therein closed by said manually operated means and by the placing of the ammunition in the hoist compartments.

These and other objects and advantages of the invention will be fully set forth in the following description made in connection with the accompanying drawings in which like reference characters refer to similar parts throughout the several views and in which: I

Fig. 1 is a diagrammatic view illustrating the hoist hydraulic control and driving means together with the flight control mechanism and the various electrical and hydraulic control mechanisms;

Fig. 2 is a view of a portion of the control mechanism shown in a difi'erent position than in Fig. 1, the same being shown in positions for the start of the hoisting cycle;

Fig. 3 is a view similar to Fig. 2 showing the parts in position for the deceleration period of the hoisting cycle;

Fig. 4-is a view partly in plan and partly in vertical section taken substantially on line 4-4 of Fig, 7 as indicated by the arrow;

Fig. 5 is a horizontal section taken on line 5-5 of Fig. '7 as indicated by the arrow;

Fig; 6 is a vertical section on line 6-45 of Fig. 1 and Fig. '7 is a partial View similar to Fig. 1 shown on an enlarged scale.

Referring to the drawings, a shaft Ill is shown upon which are secured spaced sprockets I I which will constitute the driving sprockets for the hoist. The hoist (not shown) comprises an endless conveyer moving in a housing and driven by sprockets II having spaced supports thereon for receiving the shells or other ammunition, said housing having upper and lower doors. Switches are provided at these doors which will be later described. Shaft It is driven through a speed reducing mechanism 12. While this speed reducing mechanism may be of various types, one common type is that of a worm and worm wheel. reducing mechanism is driven from a hydraulic motor [3 which may be of standard type or form. Such motors are well known in the art. Hydraulic motor i3 is supplied with operating :fiuid by conduits M or 15. Conduits Hi and 65 form The speed the inlet and outlet conduits of a variable stroke 7 pump 24. While various types of variable stroke pumps might be used, one type which has been found suitable is that similar to the pump disclosed in U. S. Letters Patent No. 1,062,071, granted May 20, 1913, to H. D. Williams et al. on Speed adjusting means for rotary hydraulic devices.

A duplex relief valve is is disposed between conduits M and 15. Pump 2% as stated is of the variable stroke type and the stroke is varied by movement of rod 25 controlled by a piston 25 the passage of liquid from a passage 31 to spaced passages 37g and 37h. Passage 37g leads to the outer side of member 31 while passage 37h leads to and communicates with passage 31d. Valve 54 is engaged at its lower end by a coiled compression spring 55 which normally tends to raise said valve and said valve comprises a valve rod or stem 540 connected at its upper end to a sole noid core 55. Core 56 is disposed in a solenoid or magnet coil 57, the ends of which are connected respectively to conductors 58 and 59. Core 56 has a cylindrical head movable in a cylindrical chamber in a casing 6i). A plunger 6| extends through a bore in casing 60 into said chamber and into engagement with the head of core 58. Plunger Si is adapted to be depressed manually at certain times as will be later described. Said plunger BI is held in the position shown by a bar which may be referred to as the servo-piston.

Changing the stroke of pump 2d rotates a trunnion shaft 2'! to which is secured a gear segment 28 meshing with a gear 29 carried on a shaft 39. A control cam 3! is secured to shaft 35 and engaged by a cam roller 32 secured adjacent one end of a link or lever 33. Piston 25 is movable in a cylinder 33 having ports 34a and 34b adjacent its ends with which ports communicate conduits 35 and 36. Conduits 35 and 36 are connected to a control unit comprising a member 37. Member 37 has therein a valve chamber 37a illustrated as of cylindrical form and contained within a bushing or lining 38. A valve 46 is movable in valve chamber 31a and has spaced portions or lands 40a, Mlb and 400. Ports or passages 37b and 370 lead from valve chamber 31a to and communicate with conduits 35 and 36 respectively. Another passage 3id extends from valve chamber 3'ia to and communicates with a condui-t 41 forming the outlet or discharge passage from an auxiliary or pressure maintaining pump 42, often called a make-up pump. Pump 42 is driven from pump 2 3 by a shaft 2%. Pump a2 is really a double or duplex pump having inlet conduits 43 and M communicating with a conduit 45 leading to oil reservoir 46. A filter Ma is shown in conduit 3!. Passage 3701 may be varled in size or cross sectional area by a plug 39 threaded into member 3?, the same being shown as having a-slotted head and being equipped with a jamb nut 39a (see Fig. 5). Valve 4% comprises a valve rod 48d which is connected'to lever 33. A fork member 48 connected to rod 43d has portions disposed at either side of lever 33 and connected thereto by suitable studs 48. Rod Add is thus pivoted to lever 33. It may be stated that a headed plunger 55! bears on lever 33 adjacent roller 32. Plunger 55 has a piston head 530; movable in a cylinder 5! and engaging a coil compression spring 52, the other end of which engages cylinder 5 Plunger 553 thus acts to hold the end of lever 33 in position with cam roll 32 pressed against cam 3!. Member 3'! has therein a bore 3le forming a valve chamber in which is movable a valve 54 having spaced cylindrical portions or lands 54a and 5th. Valve 54a controls 510. which is secured by a padlock 51b. A bellows 62 is engaged by an intermediate portion of rod 540,-anut 63 being secured to rod 5&0 for this purpose. a

Member 37 has therein a valve chamber Eli. Chamber 312 is connected to passage 31 by the spaced ports 317' and (ilk. A passage 31m com municates with valve chamber 310. adjacent the lower end of said chamber and extends to and communicates with valve chamber 312 some distance above port 31k. Passage 31m has a passage 3ln extending upwardly therefrom, the same having a port 370 communicating with valve chamber 3'12 adjacent the top of the latter. A drain or vent conduit 65 extends from passage 3711 to a similar conduit M5 later described. A passage 31p has a port opening into valve chamber 311' substantially midway between ports or passages 37m and 310, the same extending to the top of member 31 and communicating with a conduit l0 which is connected to the discharge chamber of pump 24. Another conduit ll extends from conduit H! the discharge chamber of pump 52. A vent or relief passage 3lq extends from passage 31m adjacent valve chamher 312' and communicates with valve chamber 312 some distance below the pointwhere passage 31k communicates with said valve chamber. A passage 311 communicates with valve chamber 312' somewhat adjacent the lower end thereof, said passage extending to and communicating with a conduit 12 which extends to a member I3 forming part of the flight control mechanism which will be later described. A passage 3'is leads from valve chamber 372' to adjacent the top of another valve chamber 371E formed in member 31. Another passage 3% leads from valve chamber 371' some distance below passage 37s and communicates with valve chamber 312? adjacent the bottom thereof. Passage 3111. has a constricted portion therein between valve chambers 312 and 3%. A by-passage 3711 connects with passage 31a and extends about said constricted portion, said passage 312; having a check valve 74 therein. A valve 15 is disposed in valve chamber 372', the same having a plurality of spaced portions or lands a, b, c, d, e and 1 ntting in valve chamber 312'. Said valve has a valve rod or stem 75g which extends below member 3'! and is connected adjacent the end of a hand lever 76 pivoted on a stud Tl. Valve 75 may be called the selector valve and lever 16 the selector lever. Lever 16 is movable to three positions as indicated in Fig. 1, namely, the hoist or lifting, neutral and lower or lowering positions. Lever 76 is shown as having an extension at its end connected by a link 78 to a double switch I having a contact Ida movable to connect or disconnect conductors 80 and BI and a contact 191) adapted to connect or disconnect conductors 82 and 83. Switch 19 may be called the selector switch. A piston 85 illustrated as having a single cylindrical portion or land is disposed in valve chamber 311., the same having a rod or stem 85a, the upper portion of which projects above member 31 and is secured to a-fork member 86 having arms extending at either side of member 33 and pivoted thereto by studs 81. Member 33 is thus connected at spaced points to valve 40 and piston 85. The lower portion of rod 85a extends into a cylindrical chamber 32w formed in member 31 axially alined with valve chamber 3125. A bushing 89 is disposed in the lower end of chamber 37w, the inner end of which is engaged by a washer 90 surrounding rod 80a and engaged by the lower end of a compression celled spring 9I, the upper end of which engages a washer 92 which seats against the shoulder formed by a reduced portion of chamber 31w. A nut or collar 93 of a size to move into said reduced portion is secured to red a and engages the top of washer 02.

A shaft 90 is connected to the speed reducing mechanism I2 and rotates in fixed ratio with shaft I0. Shaft 96 has secured thereto a beveled pinion 9i meshing with a beveled gear 90 which has secured thereto a drum or block 99 from the end of which opposite gear 90 projects a plurality of pins I00. Pins I00 are shown as four in number and spaced equally circumferentially about the end of drum 09. Gear 98 is secured to a shaft 900 journaled in a casing 61. Drum 99 has formed therein chambers 99a extending parallel to the axis thereof. Each pin I00 has a head disposed in one end of one chamber 99a, said pin being slidable in a bore extending from said chamber to the outer end of said drum. A coiled compression spring it?! bears against one end of said chamber, the other end of which bears against the head of pin I00. Pins I00 are thus normally moved to their outer positions shown in Fig. 4 by springs i02. Each chamber 00a has a port or passages!!!) leading from adjacent the outer end of chamber 99a to the periphery of drum 90. A member I04 .ene gages the side of drum 00 fitting tightly thereagainst, the same having a reduced cylindrical portion IMa extending into a bore 13a formed in member". A compression coiled spring I05 has one and engaging the end of bore 13a and its other end being disposed in a bore in portion IMa. Spring I05 thus acts to hold member I04 against drum'09. Member I04 has a passage i041) therein leading into chamber 13a and member I3 has therein a passage 131) leading into chamber 13a, which passage 131) communicates with conduit I2. Member 33 previously referred to is bored to receive a member I08 which is slidable therein, member I08 having a bore I08a therein. A coiled compression spring I09 is disposed inbore I08a having one end bearing against the end of said bore and the other end bearing against the bore in member 33 so that said spring normally forces member I08 outwardly from member 33. Member 108 has formed thereon or secured thereto at its outer end a detent portion or member IIO. As shown in Fig. 1 member IIO extends vertically some distance above and below member 33 and its carrying member I08 and the same has a convexly curved outer surface. Member IIO has a groove formed therein midway of its outer surface in which 'one of'the pins I00 is adapted to seat in the operation of the device.

Pump 24 has a driving shaft 24a to which is secured a gear II5 meshing with a gear 6 secured to the driving shaft II? of an electric motor H8. The usual conductors IIO are shown extending to'motor I I0, which extend to a controller I20 which may be of any well known type. A starting switch I2I of the button type is also shown connected to controller I20 by conductors I22.

Shaft I0 of the hoist extends into a casing I25 and has secured thereto a ratchet wheel I26. A plunger I2! is slidable through the top of casing I25 and acts as a pawl or stop detent'to engage ratchet wheel I26. Plunger I21 has a head I2'Ia forming a piston slidable in a cylindrical casing I250, extending upwardly from the top of easing I25. A coiled compression spring I28 is disposed above plunger head IZ'l'a and engages the top thereof, the other end of said spring engaging the top of easing I25a. Casing I25'a has a port or opening I251) in the side thereof with which communicates a conduit E30 which is connected to conduit 4| leading from make-up pump 42. It will be seen that when pump 42 is operating pressure will be maintained in casing I25a beneath piston I2'Ia so that plunger I2I will be maintained out of contact with ratchet i2I5. Should there be no pressure in casing I250; spring I28 will force plunger I2! into position to engage against ratchet wheel I20. This will prevent rotation of shaft I0 in the direction opposite to the arrow shown in Fig. 6 and will prevent lowering of the hoist.

A conduit Hi5 is connected to conduit 1!, said conduit being connected by conduit I45 to oil reservoir and by conduit I l-3 to pump 24. A relief valve MM is shown in conduit I45 and in one embodiment of the invention in practice this has been set to open at fifty pounds pressure. A conduit I55 also connects conduit I45 to conduit 4|. A relief valve I55a is disposed in conduit I55. In one embodiment of the invention in practice this valve has been set to open at 250 pounds pressure. Conduit I55 also extends to casing I25a. Conduit I45 and the conduits attached thereto act as relief or equalizing conduits conveying the oil to reservoir 40. The valve casing 31 and adjacent parts will be contained in a casing indicated as I41 which preferably will contain oil. An equalizing conduit I50 extends from the top of oil reservoir 46 to the top of casing IN.

A conduit I52 extends from one side of the casing of pump 24 adjacent the bottom thereof to conduit 'I I. A check valve I53 is disposed in conduit I 52 adjacent pump 24. A conduit i050 extends from the lower portion of unit 93 to the top of pump 24.

As previously stated there is an upper door switch on the hoist and this is shown in Fig. 1 as switch I60. Said switch is shown as adapted to connect a conductor Iti and a conductor I59, which conductors extend to motor controller I20. The lower door switch of the hoist is shown in Fig. l as I02. Switch I02 is adapted to connect a conductor I64 and a conductor 03 which extends to motor controller I20. A pair of push button switches are provided, one of which, I65, called the upper push button, is adapted to connect a conductor 166 to conductor 50. Conductor I06 extends to the other push button switch I10 and is adapted to be connected thereby to conductor BI. A cam switch III is shown in Fig. l adapted-to connect conductor 59 toa' conductor I12. Conductors I64 and 80 are adapted to be connected by a switch I14 connected to a rod I15 which also carries a switch I16 adapted to connect conductors 82 and I12. Switch I14 may be referred to as the lower cam switch. A hand lever I80 has a portion adapted to be moved to engage rod I15 so as to operate switches I14 and 118. It'will be noted that upon downward movement of rod I15 as shown in Fig. 1 switch I15 will be moved to closed position while switch I14 will be moved to open position.

As stated the hoist comprises an endless conveyer which is moved in a series of comparatively short movements or flights. With the embodiment of the invention illustrated the mechanism was designed in one specific case for flights from 49 inches to approximately 56 inches. It is desirable and, in fact, almost necessary that the hoist start from rest at the beginning of the flight, be accelerated quickly to maximum velocity and then be decelerated at a predetermined rate to come to rest at the end of the flight.

Referring to the control of the variable stroke main pump 24 by the servo-piston 2% it will be seen that the servo-valve 40 is in neutral position. If this valve is forced downwardly from neutral, liquid or specifically oil which is commonly used, will flow under pressure from auxiliary pump e2 through conduit 4| and passage 31d past the upper end of land 4% and into the chamber between this land and land 40a out through passage 31c and through conduit 35 to the right hand end of servo-piston 26 as seen in Fig. 1. This will force piston 26 to the left, thus moving rod 25 to the left. This acts to increase the stroke of pump 24. Oil from the left hand end of piston 25 is forced through conduit 35 and passage 3113 into the lower end of valve chamber 3111 between portions 402) and 4190 of valve 40, thence through passage 31m and through conduit 65 into the oil reservoir. By movement of rod 25 the trunnion shaft 21 is oscillated and gear segment 28 is moved thereto to rotate gear 29. This rotates control cam 3 I, which acting upon roller 32 raises the left hand end of link 33. This lifting of link 33 lifts valve rod 40d and moves servo-valve lll back toward its neutral position. As soon as this neutral position is reached oil flow to the servopiston 26 through the servo-valve 40 is stopped and a new position of equilibrium is established with pump 24 held on partial stroke, the magnitude of this stroke being determined by the amount of downward motion of the right hand end of member 33 and the shape of cam 3|. The actual operation of the pump, member 33 and cam 3| is continuous rather than cyclic or discontinuous as above described. In other words as the right hand end of the linkage or member 33 is being forced downwardly the stroke of pump 24 is simultaneously changed according to the action of the servo-valve and servo-piston in connection with the coacting cam 3| and said linkage.

Similarly, if the member 33 is moved upward from the zero position indicated in Fig, l the stroke of pump 25 is simultaneously changed in a direction opposite to that previously described.

lhat is, upon an upward movement of operating valve rod 49d, valve 30 will be moved above its neutral position allowing oil to flow from conduit H through passage 31d into the chamber between the portions or lands 4% and 450 of servo-valve to and oil will then flow through passage 31?) and conduit 35 into casing 36 at the left hand end of piston 26 and said piston and rod 25 will be moved to the right as shown in Fig, 1, thus again changing the stroke oppositely to that previously described. Cam 3| will be moved in the opposite direction and link 33 will be moved to bring valve 44 toward neutral position. It will be seen that pump 24 supplies oil through conduit 55 to hydraulic motor I3. Oil will pass from the motor through conduit I 4 back to pump 25. The flight control mechanism including member and the solenoid valve 5 3 control the position of the right hand end of link or lever 33 automatically in response to the electrical circuits provided.

Fig. 1 as above stated shows the unit in neutral position and with the selector valve set for the hoisting position or upward movement of the hoist. At this time the upper hoist door is open which closes the upper door switch IBII, With the unit in neutral position the electric motor H8 is in operation and pump 24 is being driven on neutral stroke. Auxiliar or make-up pump 42 is also driven through shaft Ill for maintaining the desired pressures. It will be seen that pressure is delivered to casing I2l'ia below plunger IZ'Ia through conduit 539 so that the detent plunger 21 is held out of engagement with ratchet I26. With no shell in the upper chamber of the hoist the upper cam switch I1I is closed and with no shell in the lower chamber of the hoist switch H5 is open and switch I'M is closed. Under these conditions solenoid 51 is not energized and the solenoid valve 54 is in the position shown in Fig. 1. It will be seen that one terminal of solenoid 51 is connected directly to the power line at controller I20 through conductor 58. The circuit of solenoid 51 is open at the opposite side of the solenoid. The circuit of the solenoid may be traced through conductor 59, closed switch I1! conductor I12 to the open switch I16 or through conductor 59 as before, through the upper push button switch I55 which is normally open, through conductor I66 to the lower push button I19 which is normally open and to open switch 18a. If a shell is now placed in the lower opening and the lower doors closed, switch I16 will close connecting conductors 82 and I12 and the circuit of solenoid 51 is then closed, through conductor 82, switch 15?), conductor 83, conductor l the lower door switch I62, now closed, and through conductor I53. With switch 1% thus closed by the selector lever being set for the hoisting position shown, oil under pressure in line 15 new flows through the chamber of the selecting valve, between the por tions it and b of valve 15, through passage 31s into the upper part of valve chamber 3125 and thi pressure tends to force piston 85 downward. The lower portion of chamber 312? is connected through the parallel paths 31a and 3117 and check valve 14 to the chamber in valve chamber 312' between portions 2) and c of valve 15 and then to conduit 85 through passage 31% to the oil reservoir. Piston 85, however, is prevented from mov- -il1g downward by the pressure thereon due to the fact that the linkage detent member II!) is engaged by one of the pins Iii!) on the flight control drum 99. This pin as shown in Figs. 1 and 4 is seated in the groove the curved face of member Hi). It will be seen that thi pin IE0 is positioned through gear 38, pinion 91 and shaft 96 from the hoist sprocket shaft is. However, as soon as a shell is placed in the lower chamber of the hoist and the lower doors closed, solenoid 51 is energized through the circuit just above traced and the solenoid acts to move valve 9, rod 540 downwardly, thu moving solenoid valve 54 downwardly. When this occurs, oil under pressure flows from conduit II through passage 31d and through passage 31h into valve chamber 31c and into passage 31 through the selector valve chamber 312' between portions and d of valve I5, thence into passage 311' and into conduit I2. The liquid flowing into conduit 12 enters passage 13a and acts on the differential piston area of the piston head of pin I09, forcing this pin back into the drum 99 against the pressure of spring I02, thus disengaging said pin from the linkage detent member I Ill, When said pin I00 is thus withdrawn from member I II! the pressure on piston 85 immediately moves said piston downwardly so that the parts are then in the position shown in Fig. 2. The rod 40d of servo-valve 40 isthus moved downward b member 33 and oil is allowed to flow from conduit 4| into passage 31c between the upper two lands of servo-valve 40, which oil flows through conduit 36 to the right hand side of servo-piston 26 and this piston is moved and moves rod 25, thu rapidly changing the stroke of pump 24 from zero to full stroke and the cam 3| is rotated clockwise as shown in Fig. 1 approximately 90 degrees. The speed of the stroking piston 26, the speed at which the stroke is changed and hence the acceleration rate of the hoist may be controlled by the adjustable orifice 31d, which is regulated by the plug or screw 39 shown in Fig. 5. When servo-piston 26 is moved and the stroke of main pump 24 changed from neutral in the hoisting ope-ration, oil is delivered through conduits I4 or I5 to the hydraulic motor I3 and the shaft I0 and hoist sprockets II are driven, thus causing movement of the hoist for a flight. Inasmuch as the speed of the servopiston during the stroke-changing interval is approximately constant, the acceleration of the hoist is very nearly constant and full speed operation in raising the hoist is rapidly attained.

During the hoisting operation shaft 96 is driven and the flight control mechanism is driven through gears 91 and 98. Rotation of gear 98 rotates drum or plug 99 and one of the pins I00 comes into engagement with the linkage detent member IIU. Said member H0 i raised as will be apparent from Figs, 3, 2 and 1 so that the right hand end of member 33 is raised and the valve rod 40d of the servo-valve is raised and held slightly above neutral so that oil from pipe AI now passes through passage 31d into valve chamber 31a between portions 40b and 400 of valve 40 and thence through passage 31b and conduit 35 to the left hand end of servo-piston 26. Piston 26 is thus moved back toward its zero or neutral position and the stroke of pump 24 is changed and the hoist decelerated. Since the stroke of the main pump 24 determines the speed of the hoist shaft I0, for any given position of the hoist during the deceleration cycle, there is a definite, accurately controlled speed of operation, which speed i reduced as the hoist approaches a flight level. When the flight level is reached, pin Iilil has rotated exactly 90 degrees clockwise from its initial position when the hoisting operation began which will be clearly seen in Fig. 1. At the end of said 90 degrees the servo-valve and piston are again in neutral position and the hoist is maintained stationar on a flight level providing the solenoid valve is not re-energized. It will thus be seen that the deceleration has been accurately controlled by cam 3| and the flight control mechanism. The deceleration and velocity are brought 10 to zero point as the hoist finishes its flight. The deceleration curve is substantially a straight line. The deceleration can thus be predetermined,

If, however, another shell is placed in the lower chamber of the hoist and the shell removed from the upper chamber before the hoist comes to a complete stop at the flight level, the solenoid 51 and the solenoid valve 54 are again actuated and the pin IilIl engaging member III) will be withdrawn from the linkage detent and a new hoisting cycle will be initiated immediately.

The operation of the servo-valve and servopiston 25, the operation of the linkage detent and flight control mechanism including member 33, drum $9 and attached parts is essentially the same in the lowering operation of the hoist as in the hoisting or lifting operation. With the selector lever I6 set for the lowering position oil under pressure from conduit II flows through conduit IE! and through passage 31p, through valve chamber 312', between portions b and c of selector valve 75, through passage 3'lu having the restriction therein and into valve chamber 3It below piston 85. This oil under pressure tends to force piston 85 upwardly but this motion is again prevented by one of the pins I80 being engaged in linkage detent member IIil. However, regardless of the position of the upper cam switch Ill the solenoid 5'l can be energized by simultaneous operation of the upper and lower push buttons I65 and Iii] if the lower hoist door is closed and there is no shell in ing switch I'M open. As soon as the solenoid 5'! is energized the detent pin IE8 is withdrawn by oil pressure through conduit 12 acting thereon as above described and the pressure on piston 85 forces the same upward. This raises the right hand end of member 33 but at a reduced rate depending upon the restriction in passage 31a. Valve rod 48d is thus raised and valve is moved to a position above its neutral position and oil under pressure from conduit 4! flows into valve chamber 31a between valve portions Mil) and 460, then out through passage 31b into conduit 35 and into cylinder 3d at the left hand end of servopiston 26. The piston is thus moved to the right as shown in Fig. l and the main pump 24 will have its stroke changed and oil will be delivered through conduits I l and I5 to drive motor I3 in the direction to lower the hoist. The movement of piston 26 is at a reduced rate depend.

ent, of course, upon the speed of the upward movement of the right hand end of member 33. The reduced rate of speed of piston 26 and acceleration of the hoist on lowering is to prevent shucking of the shells. The hoist is self-level ing on the lowering cycle just as has been previously described for the upward or hoisting cycle. If the upper and lower push buttons I65 and I'iil are held closed the hoist will continue to lower until a shell arrives at the lower chamber and operates the lower cam switch I'M, thus opening the circuit of solenoid 5'I. This prevents initiation of another lowering cycle. The hoist can be controlled by hand lever I which operates switches I14 and HS. These switches occupy function in the circuits as do switches 13a and 1% respectively.

The hand lever I88 is used to operate switches I! and H6. When it is desired to clear the hoist or in other words to keep it running until all the shells or other articles are removed therefrom, the operator presses down on the rod carrying switches I'M and I16, thus closing switch I16 and opening switch I14. This will cause repeated the lower chamber hold-- 11 operations of the hoist. The action is the same as placing a shell on the hoist.

From the above description it will be seen that I have provided a very eflicient and very accurately controlled hydraulic hoist system. The hoist is brought from rest very quickly to maximum velocity in a flight and is decelerated under positive control. The deceleration will be according to a predetermined rate regardless of the viscosity of the oil or control fluid. The coaction between control cam 3| and the flight control mechanism which is connected to member 33 insures that the deceleration will be accurately controlled and that there will be a flxed predetermined relation between the position of the hoist and the deceleration so that the hoist comes to rest accurately at the end of the flight and in the desired position as the deceleration reaches zero.

It will be obvious that the invention has a high degree of utility for the purpose intended and the same is being manufactured for actual use.

It will, of course, be understood that various changes may be made in the form, details, arrangement and proportions of the parts, without departing from the scope of ap'plicants invention, which generally stated, consists in a device capable of carrying out the objects above set forth, in the parts and combinations of parts disclosed and defined in the appended claims.

What is claimed is:

1. A hydraulic system for operating a hoist having in combination, a hydraulic power unit for moving said hoist, a variable stroke pump for driving said unit, means for varying the stroke of said pump to control the rate of movement of said hoist, a control means for said last mentioned means including a valve, a cam moved in accordance with the change of stroke of said pump, a flight control mechanism driven from said hoist includin a revoluble member having circumferentially spaced means thereon, a lever moved by said cam and having a portion extending to adjacent said revoluble member and adapted to be engaged by one of said spaced means for moving said valve and controlling the deceleration of said hoist, said lever being connected to said valve intermediate said cam and said revoluble member.

2. A hydraulic system for operating a hoist having in combination, a hydraulic power unit connected to said hoist for moving the same, a variable stroke pump for driving said unit, means for changing the stroke of said pump for controlling the rate of movement of said hoist, a hydraulic valve for controlling said means, mechanism moved in accordance with the change of stroke of said pump connected to said valve and a flight control means driven directly from said hoist also connected to said mechanism for moving said valve, said flight control means including a rotatable member, a plurality of circumferentially spaced members carried by said member adapted to respectively engage said mechanism and hydraulic means for moving said last mentioned members to inoperative positions.

3. A hydraulic system for operating a hoist having in combination, a hoist, a hydraulic power unit connected to the hoist for operating the same, a variable stroke pump for supplying liquid under pressure to said unit, a hydraulic means for changing the stroke of said pump, a valve for controlling the supply of liquid to said hydraulic means and a cam operatively connected to the stroke changing mechanism of said pump 12 and moving in accordance with the change or stroke of said pump for controlling the position of said valve.

4. A hydraulic system for operating a hoist having in combination, a hoist, a hydraulic power unit connected to said hoist for moving the same,

a variable stroke pump for driving said unit,

means for changing the stroke of said pump to control the rate of movement of said hoist, a hydraulic valve for controlling said means, a cam moved in accordance with the change of stroke of said pump, a flight control mechanism driven from said unit and a difierential mechanism connected to said valve and simultaneously acted upon by said cam and. flight control mechanism for positioning said valve to determine the deceleration of said hoist.

5. A hydraulic system for operating a hoist having in combination, a hydraulic power unit for moving said hoist, a variable stroke pump for driving said unit, hydraulic means for changing the stroke of said pump, a valve for controlling said hydraulic means and means moved by and in non-linear relation to the change of stroke of said pump for controlling the movement of said hoist and means moved in direct relation to the movement of said hoist for controlling the movement of said valve to control the deceleration of said hoist, said last two mentioned means being connected for simultaneous coaction.

6. A hydraulic system for operating a hoist having in combination, a hydraulic power unit connected to said hoist for moving the same, a variable stroke pump for driving said unit, a hydraulic means without said pump for changing the stroke of said pump to control the acceleration of said hoist, a cam moved in accordance with the change of stroke of said pump, a lever mechanism acted upon by said cam, a control means for said means positioned by said lever mechanism, a flight control mechanism driven from said unit and acting upon said lever mechanism to control the deceleration of said hoist, said control means being normally held by said flight control mechanism in position to hold said pump in substantially neutral stroke with said hoist stationary and manually controlled hydraulically operated means for releasing said control means from said flight control mechanism to permit movement of said first mentioned means and said hoist.

7. A hydraulic system for operating a hoist having in combination, a hydraulic power unit connected to said hoist for moving the same, a variable stroke pump for driving said unit, means for changing the stroke of said pump for controlling the rate of movement of said hoist, means moved by the change of stroke in said pump including a cam, a valve for controlling said first mentioned means, a flight control mechanism driven in direct ratio to the movement of said hoist, a member carrying a roller engaging said cam and connected to said valve, said member having a portion disposed adjacent said flight control mechanism to be engaged and moved thereby after said hoist is in motion to control said valve and to eflect deceleration of said hoist.

8. A hydraulic system for operating a hoist having in combination, a. hydraulic power unit connected to said hoist for moving the same, a variable stroke pump for driving said unit, means for changing the stroke of said pump for controlling the movement of said hoist, means moved in direct relation to the change in the stroke of said pump including a cam, a valve for controlling said first mentioned means, a lever operated at one end by said cam, a flight control mechanism having means engaging and moving the other end of said lever during the latter part of movement of said hoist to control the deceleration of said hoist, said lever being connected to said valve between said last mentioned means and said cam.

9. A hydraulic system for operating a hoist having in combination, a hydraulic power unit for moving said hoist, a variable stroke pump for driving said unit, means for changing the stroke of said pump for controlling the rate of movement of said hoist, a cam moved in accordance with the change in stroke of said pump for controlling the acceleration of said hoist and means driven in direct ratio with said unit and coacting with said cam after said hoist is in motion for controlling the deceleration of said hoist.

10. A hydraulic system for operating a hoist having in combination, a hydraulic power unit for moving said hoist, a variable stroke pump for driving said unit, a member movable to change the stroke of said pump, a control means for said member including a valve, a cam actuated by the movement of said member, a lever acted on by said cam, said valve being connected to the intermediate point on said lever, a second member driven from said unit constructed and arranged to engage the other end of said lever after said hoist is in motion for controlling the deceleration of said hoist.

11. The structure set forth in claim and a manually controlled hydraulically operated piston connected to said lever for initiating the movement of said valve and member.

12. A hydraulic system for operating a hoist having in combination, a hydraulic power unit for moving said hoist, a variable stroke pump for driving said unit, a member movable to change the stroke of said pump, a control means for said member, a lever connected intermediate its ends to said control means, a connection between one 14 end of said lever and said member producing a non-linear movement of said lever, a second member constantly driven in direct ratio to said hoist for engaging the other end of said lever for controlling the deceleration of said hoist.

13. The structure set forth in claim 12 and a manually controlled means connected to said lever for moving said control means for initiating movement thereof and of said first mentioned member.

14. A hydraulic system for operating a hoist having in combination, a hydraulic power unit for moving said hoist, a variable stroke pump for driving said unit, hydraulic means for changing the stroke of said pump, a control means for said hydraulic means, means moved in relation to the change of stroke of said pump for controlling the movement of said hoist, and means moved in relation to the movement of said hoist for actuating said control means for controlling the deceleration of said hoist, one of said last mentioned means being constructed and arranged to make one of said relations a non-linear relation.

GAROLD A. KANE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,861,116 Ernst May 31, 1932 2,093,690 Wiedmann Sept. 21, 1937 2,129,613 Wiinsch Sept. 6, 1938 2,139,185 Engel Dec. 6, 1938 2,148,262 Doe Feb. 21, 1939 2,148,277 Rose Feb. 21, 1939 2,211,406 Cannon Aug. 13, 1940 2,213,968 Rose Sept. 10, 1940 2,227,170 Ziebolz Dec. 31, 1940 FOREIGN PATENTS Number Country Date 404,385 Great Britain Jan. 18, 1934 

